Method of making catalyst



proved atented July 22, 1924.

UNITED STATES 1,502,336 PATENT OFFICE.

LUIGI oAsALE, or some, ITALY, assrenoa 'ro CASALE mom comm, or

. memo, swrrznarm.

METHOD 0]? MAKING CATALYST.

No Drawing.

To all whom it may concem:

Be it known that I, LUIGI OAsALn, a citizen of the United States, andresiding at Rome, Italy, have invented a new and Im- Method of MakingCatalyst, of which the following specification is a full disclosure.

This invention deals with the preparation of so-called catalyticmaterial suitable for accomplishing the formation of ammonia by causinghydrogen and nitrogen to combine when subjected, under appropriateconditions, to the action of the catalyst. Various substances are knownto possess catalytic properties of this nature but commerclalconsiderations demand the use of inexpensive ingredients and likewiserequire that the method employed for im-.

partin catalytic properties to the material used s all be not only aninexpensive and easily performed method but also shall produce greatcatal tic efficiency.

Iron, either a one or with other elements, has heretofore beenascertained to be a satisfactory catalyst but its catalytic effectivityhas varied widely in accordance with the procedure adopted for itspreparation. Iron is initially obtainable only in association withcertain impurities having a detrimental influence on the catalyticactivity. These so-called poisons include such elements as sulphur,phosphorus, arsenic, etc., and, to eliminate them, has been one of theproblems confronted by the art. The

" prior methods most nearly meeting commercial considerations haveinvolved, as a step, the use of oxygen gas for oxidizing the iron; thematerial beingsubjected to a stream of the gas under moderate condi- 40tions under which the iron or its oxide has been brought as high as thepoint of fusion. The mass was then allowed to cool and solidify andsubsequently was reduced in hydrogen gas. It was found that, by startingwith sufficiently pure iron, catalytic properties could be impartedtothe iron.

This invention is based upon the discovery that if the oxidation becarried out under conditions of extreme violence, in-

stead of moderately as heretofore, that a ronounced improvement would berealized 1n the catalytic activity of the ultimate product. That is tosay this invention proposes not merely to employ oxygen gas insufficient quantities to oxidize the material Application filed August22, 1923. Serial No. 658,828.

and bring it into a condition of fusion, but to carry out the oxidationwith such exceed ng rapidity and simultaneity as to all part1cles of thematerial, that the heat engendered will produce not only a fusion of theentire mass but will attain a tem perature greatly in excess of thefusion point; so much as to rise to the vaporizat1on point and cause thematerial to boil so violently that much of it escapes in a cloud ofvapor carrying away the above mentioned poisons in vaporous form. It iswould assume an allotropic state, especially active, and this might playan important part in determining catalytic activity. As an illustrationof the radical treatment characterizing this step of the process, itmaybe explained that the oxygen gas is to be supplied, not in the form of amoderate stream, but as a powerful blast, i. e., in such overwhelmingquantities as would be delivered by a nozzle say of 6 cm. in diameterunder a gas pressure of about 10 atmospheres and projecting the jet ofgas either against or through a moderate amount of the material say 5 or6 kg. It will be understood, of course, that the combustion will beinitiated in any suitable manner, as by an igniter such as the flame ofa Bunsen burner, and forthwith the oxidizable ingredients in thematerial will spontaneously take fire and burn (oxidize) with almostexplosive violence; the entire interval of complete oxidization beingalmost instantaneous and under such excessive temperatureconditions(about 2,000 O.) that from 10 to 20% of the entire mass willbe volatilized and all so-called poisons will likewise be volatilizedand swept away in the rush of escaping ,gases. It has been demonstratedby exhaustlve commercial tests that this treatment, as a step inimparting catalytic properties to iron containing material, is extremelyeffective and may be resorted to successfully whether the materialtreated be virtually pure or whether it contains considerable quantitiesof poisonous elements, or whether it contains additional elements havingalso catalytic or beneficial characteristics. One distinct advantage ofthis excessively high temperature treatment, as an oxidizing step, isthat it renderss the oxidized product entirely homogeneous as to thedistribution throughout its mass of probable that at or above 2000 C.the iron the various elements remaining thereinand,*

' accordingly, when the mass is subsequently broken into small piecesand when these are subsequently reduced by hydrogen, each of theresultant subdivisions of the catalyst are alike in composition and areequally effective in a catalytic sense; a result that has heretoforebeen unattainable by the pre-' 'vious moderate conditions of oxidationwhich merely produced what may be termed an incipient fusion of themass. I

This invention, accordingly, contemplates a process of preparing acatalyst by first subjecting the material to an excessively intense heatsuch as will quickly volatilize a considerable proportion of the entiremass including especlally such poisons as sulphur, arsenic,phosphorusand the like and which will, by virtue of the violent ebullition of mixtogether all of the remaining ingredients or elements so as to produce athoroughly homogeneous mixture of oxides. -VVhen subsequently reduced bythe action of hydrogen, in any appropriate manner, the resultant productwill be rendered highly catalytic. This subsequent step may be performedby passing hydrogen through the.

broken up material in a separate container and the resultant catalystmay then be placed in the catalyzing tube of the ammonia formingapparatus, or, the broken-up oxidized material maybe placed directly inthe catalyzing tube and the hydrogen may be passed through such tubeuntil the reduction has been completed; whereupon the resultantcatalytic material will continuethereafter to cause the hydrogen andnitrogen passing through the tube to be combined to form a.) ammonia.

Various materials, or mixtures of ingredients, maybe initially subjectedto the intense oxidizing treatment. It'is not essential to start withpractically pure metals although the treatmentis successful with puremetals. Traces of sulphur, phosphorus and the like are not onlyunobje'ctionable' but even are advantageous in the sense that theirvcombustion assists in creating the excessively intense heat which isessential and these poisons escape, as aforesaid, in vaporous form.

Even iron that has, through prolonged use as a catalyst, become poisonedand has lost its catalytic properties, may be restored to its originalactivity by intensive treatment. In t at case, it is desirable to mixthe poisoned catalyst with some material possessing a high heat of com'-bustion, as for example, carbon or even ordinary coal. Under the violentblast of oxygen the iron and the coal in the mass will oxidize violentlyand the whole mass will be brought to the intense tem erature abovedescribed and will be rendere homogeneous the fused mass, thoroughlyvand uniformly duce the results-herein set metals of the iron as provedby experience,

resorting to this 1 will be found to be restored (when subsequentlyreduced) fully to its original catalytic powers.

Further investigations have also demonstrated'that it is desirable tocarry out the aforesaid violent oxidation in the presence of certainother elements, the oxides of which are irreducible by means ofhydrogen; theseelements being, for example, alkali metal oxides, alkaliearth-metal oxides such as calcium oxide and also oxides of magnesium,aluminum and the like. These irreducible oxides, in this process, and bythe reason of the high temperature thereof are dissolved inthe fusedmass and may be employed beneficially to the amount of over 10% and forma thoroughly homogeneous mixture with the iron oxide so that in theultimate catalyst, they increase the surface of the mass and,accordingly, increase the exposure of'thecatalytic material to thehydrogen and nitrogen in the process of forming the ammoma.

Magnesium, titanium,

aluminum, calcium, ferronese, ferro-silicon and iron pyrites possesshigh heats of combustion and consequently may be advantageously employedto facilitate the extremely excessive temperatures which, as aforesaid,are indispensable for the product of a good catalyst. When these areemployed, it becomes possible to utilize artificial or natural ironoxides, or oxides of metals belonging to the iron group, or compoundsyielding iron, inasmuch as the intense heat generated by the oxidationunder the powerful blast of oxygen of the firstmentioned combustiblematerials will proforth thereby in a most efiicient manner utilizingcertain irreducible oxides which have the power of enhancing thecatalytic capacity of iron. and metals belonging to the iron group.

These oxides capable of increasing the catalytic activity of the ironand other group may be used as such, mixed with the oxides of saidmetals, but it may also be suitable to use instead of them the metalsthey are obtained from, which metals having avery high oxidation heatfacilitate the obtainment of those very high temperatures which areindispensable, for producing a good catalyst.

A convenient method of carrying out the oxidation in a practical way isto line a suitable crucible, as of cast iron, with powdered iron oxideobtained by a previous performance of the process. This powdered ironoxide may be mixed with calcined dolomite and the crucible may be linedby first covering its bottom with a layer of the mix ture. A tube ofsheet iron may then be set on the lined bottom and the mixture. 130

used for the lining may then be packed and compressed in the annularspace between the sheet iron tube and the wall of the crucible. Thisprovides a receiver in the nature of a lined crucible.

Within the central chamber is placed the material to be oxidized whichmay either be a mixture of iron oxide and coal containing additions ofpredetermined quantities of aluminum, calclum, magnesium and the like;if desirable in elemental form. Or, in the central chamber may placedthe iron together with weighed quantities of the irreducible oxides, orsubstances easily converted to same, such as bauxite, magnesia, lime,dolomite and the like, which it is desired to have dissolved in theultimate fused iron oxide. Or, any other of the materials hereinmentioned may be placed in a central chamber. The oxidation is thencarried out by the powerful blast of oxygen, as aforesaid.

This process will, therefore, be perceived to be entirely satisfactoryfor converting various sources of iron into catalytic material. Ordinaryiron or steel turnings or filings produced as waste by machine shops maybe employed, or native iron ore such as magnetite may be used, andlikewise, old waste catalytic material which has become poisoned may berestored to its original activity.

I claim:

1. A catalyst-preparing process wherein, as a purifying step, the impuremixture of oxides is subjected to a temperature so far exceeding themelting point of the mixture as to vaporize not only a considerableproportion of the useful oxides but also all elements in the nature ofpoisons capable, if remaining in the ultimate product, of exercising adetrimental effect on its catalytic properties.

2. The operation of preparing a mixture of oxides suitable for subseuent reduction by hydrogen to a catalyst w ich consists in subjecting anignited metal-containing mixture to a powerful blast of oxygen toproduce a confiagration of the mass so intense that its temperature willgreatly exceed the melting point and cause not only a violent boiling ofthe melted material and thereby intimately and uniformly mix itsresidual ingredients but also cause all the detrimental substances to bevaporized and driven off as such.

3. A method of making a catalyst of oxide-containing material consistingin first mixing the same with a readily oxidizable substance to producea-'mixture capable of' rapid combustion, then subjecting said ignitedcombustible mixture to a powerful blast of oxygen to develop atemperature of about 2000 C., then allowing the mass to cool; thenbreaking it into fragments; and then subjecting said fra ments at anelevated temperature to hy rogen to develop catalytic properties. v

4. The art of roducing a homogeneous catalyst composed of a highlyactive metal and an intimately associated compound irreducible byhydrogen for increasing the active surface of the catalyst, said artconsisting in subjecting an easily-oxidizable mixture containing saidmetal and an element of said compound to a powerful blast of compressedoxygen to roduce a violent and rapid confiagration 0 said mixture at atemperature -adequate to cause an extremel vigorous ebullition of themelted metalllc oxides to dissolve and uniformly distribute therein allresidual oxides irreducible by hydrogen and to volatilize and dissipateas a vapor all elements detr1 mental to catalytic activit thenpermitting the purified molten oxldes to cool; and then fragmentizingand reducing the same by a mixture of nitrogen and hydrogen.

In witness whereof, I hereunto subscribe my name, as attested by the twosubscribing witnesses.

LUIGI CASALE. Witnesses:

REUN Lnrnx'rz, W. E. BANN.

